Security of user credentials for L2TP remote access

I was wondering about the security of the user credentials configured on the Balance router for remote user access using L2TP. I am able to see the plain text passwords for all user accounts from the admin web interface and that’s not too reassuring.

How are those credentials protected on the router? This is relevant since the router itself is the most exposed piece of equipment, isn’t it?

Thanks a lot.
Mihnea